Question Answering (QA) research manly regards two tasks: (i) AS2, which, given a question and a set of answer sentence candidates, consists in selecting sentences (e.g., retrieved by a search engine) that correctly answer the question; and (ii) Machine Reading (MR) or reading comprehension [1]}, which, given a question and a reference text, involves finding an exact text span answering it. AS2 research originated from the TREC competitions [2]}, which target large databases of unstructured text.
